1. Field of the Invention
The present invention relates to a keyboard bracket and more particularly, to a self-locking keyboard bracket, allowing the user to conveniently adjust the elevation and angle of the supporting frame.
2. Description of Related Art
Following fast development of information industry, computer is becoming a popular equipment used in office as well as at home for paper working to substitute conventional writing apparatus. In consequence, computer peripheral apparatus such as keyboard and mouse have come intimate partners of a computer user. However, regular computer peripheral apparatus occupy much installation gap space. It is difficult to find a gap space on the limited area of the top of a table for receiving a computer peripheral apparatus. It is also inconvenient to operate a computer peripheral apparatus on the top of a table. When installed a computer peripheral apparatus, the elevation and angle of the computer peripheral apparatus may not fit the user perfectly, and the user may ache all over within a short period of time in operating the computer peripheral apparatus. In order to eliminate this problem, adjustable bracket means may be used to support a computer peripheral apparatus on a table for convenient use.
FIGS. 1A˜1C show a conventional keyboard bracket for supporting a keyboard on a table. The structure of keyboard bracket comprises a holder base 10, a connecting frame 20, a limiter 25, an adjustment control set 30, a first torsional spring 24, a keyboard support 26, a second torsional spring 28, and a locking mechanism 36. The holder base 10 is a substantially -shaped solid frame. The connecting frame 20 is a substantially -shaped frame bar having a first pivot hole 21 at one end, a second pivot hole 23 at the other end, and a smoothly arched sliding slot 22 adjacent to the first pivot hole 21. The first pivot hole 21 and the smoothly arched sliding slot 22 of the connecting frame 20 are respectively pivoted to the holder base 10 by a first pivot pin 11 and a second pivot pin 12. The limiter 25 is a flat rod member longitudinally suspended inside the connecting frame 20, having a pivot hole 252 disposed at one end and coupled to the second pivot pin 12 and a longitudinal sliding slot 253 disposed at the other end and coupled to the second pivot hole 23 of the connecting frame 20. The adjustment control set 30 comprises a pivot pin 31 pivotally fastened to a pivot hole 261 in one end of the keyboard support 26 and the second pivot hole 23 of the connecting frame 20 and the longitudinal sliding slot 253 of the limiter 25, a traction plate 32 coupled between the pivot pin 31 and the keyboard support 26, a barrel 34 sleeved onto the pivot pin 31 and stopped between the locking mechanism 36 and the traction plate 32, a spring member 33 mounted on the pivot pin 31 and stopped between the traction plate 32 and one end of the barrel 34, a cushion 37 mounted on the pivot pin 31 and supported between the traction plate 32 and the spring member 33, and washers 35 mounted on the pivot pin 31 at the two distal ends of the barrel 34. The first torsional spring 24 is mounted on the first pivot pin 11 and connected between the holder base 10 and the connecting frame 20. The keyboard support 26 is shaped like a channel bar for supporting a keyboard or computer peripheral apparatus. The second torsional spring 28 is mounted on a pin in the keyboard support 26 and connected between the connecting frame 20 and the keyboard support 26. The locking mechanism 36 comprises an eccentric block 36 coupled to the pivot pin 31, the eccentric block 36 being a parallelogram having a long side 362, a short side 364, and an arched opening 363, a locating block 365 extended from one side of the eccentric block 36, and a handle 367 fastened to the locating block 365 for turning the eccentric block 36. By means of operating the handle 367 to turn the eccentric block 36 relative to the keyboard support 26, and the limiter 25 and the traction plate 32 can be loosened, enabling the keyboard support 26 to be adjusted to the desired elevation or angle.
Referring to FIGS. 2A and 2B, when wishing to adjust the elevation or angle of the keyboard support 26, operate the handle 367 to move the eccentric block 361, causing the position of the arched opening 363 of the eccentric block 361 to be changed through 90° angle relative to the pivot pin 31. At this time, the long side 362 of the eccentric block 361 is moved into contact with one washer 35 against the barrel 34, and the short side 364 of the eccentric block 361 is moved to the axial direction of the pivot pin 31, and therefore the eccentric block 361 occupies less axial gap space around the pivot pin 31, allowing the spring member 33 to push the barrel 34 outwards. Upon outward displacement of the barrel 34 along the pivot pin 31, the limiter 25, the cushion 37 and the traction plate 32 are loosened.
Referring to FIGS. 3A and 3B, when wishing to adjust the angle of the keyboard support 26, operate the handle 367 to loosen the keyboard bracket as stated above, and then turn the keyboard support 26 about the pivot pin 31 relative to the connecting frame 20 to the desired angle, and then turn the handle 367 in the reversed direction to force the short side 364 of the eccentric block 361 against the washers 35, the barrel 34 and the spring member 33, and at the same time the long side 362 of the eccentric block 361 is moved to the axial direction of the pivot pin 31 to occupy more axial gap space around the pivot pin 31, and therefore the barrel 34 is forced into the inside of the keyboard support 34 to compress spring member 33 against the cushion 37, the limiter 25 and the traction plate 32, and therefore the keyboard support 26 is locked to the connecting frame 20.
When wishing to adjust the elevation of the keyboard support 26, operate the handle 367 to loosen the keyboard bracket, and then turn the connecting frame 20 with the keyboard support 26 about the first pivot pin 11. Because of the keyboard support 26 is coupled to the longitudinal sliding slot 253 of the limiter 25 by the pivot pin 31, the keyboard support 26 is maintained in horizontal when turning the connecting frame 20 about the first pivot pin 11 relative to the holder base 10. When adjusted to the desired elevation, the handle 367 is turned in the reversed direction to lock the limiter 25 and the traction plate 32 again.
This structure of keyboard bracket is functional, however it still has numerous drawbacks as outlined hereinafter.
1. Simply using one adjustment control set to control the elevation and angle of the keyboard bracket does not allow the user to accurately and rapidly adjust the keyboard bracket to the desired position.
2. Upon each elevation or angle adjustment, the eccentric block is forced to rub against the respective washer, therefore the eccentric block starts to wear quickly with the use of the keyboard bracket. When the eccentric block starts to wear, the load carrying power of the keyboard bracket is relatively reduced.
3. The complicated adjustment control set greatly complicates the manufacturing process and increases the manufacturing cost.